🐛 [open-formulieren/open-forms#4827] Do not add initial_data_ref if e…

…mpty

previously, initial_data_reference=null was added to the login URL next parameters, even in cases when no initial_data_reference was specified

src/components/FormStart/index.jsx

@@ -105,6 +105,10 @@ const FormStart = ({form, submission, onFormStart, onDestroySession, initialData
     );
   }
 
+  const extraNextParams = initialDataReference
+    ? {initial_data_reference: initialDataReference}
+    : {};
+
   return (
     <LiteralsProvider literals={form.literals}>
       <Card title={form.name}>
@@ -121,11 +125,7 @@ const FormStart = ({form, submission, onFormStart, onDestroySession, initialData
             isAuthenticated={isAuthenticated}
           />
         ) : (
-          <LoginOptions
-            form={form}
-            onFormStart={onFormStart}
-            extraNextParams={{initial_data_reference: initialDataReference}}
-          />
+          <LoginOptions form={form} onFormStart={onFormStart} extraNextParams={extraNextParams} />
         )}
       </Card>
     </LiteralsProvider>

src/components/FormStart/tests.spec.jsx

@@ -115,3 +115,26 @@ it('Form start page with initial_data_reference', async () => {
     'https://openforms.nl/auth/form-name/digid/start?next=http%3A%2F%2Flocalhost%2F%3F_start%3D1%26initial_data_reference%3D1234'
   );
 });
+
+it('Form start page without initial_data_reference', async () => {
+  useQuery.mockReturnValue(new URLSearchParams());
+  const onFormStart = jest.fn();
+  const onDestroySession = jest.fn();
+
+  render(
+    <Wrap>
+      <FormStart
+        form={testLoginForm}
+        onFormStart={onFormStart}
+        onDestroySession={onDestroySession}
+        initialDataReference={null}
+      />
+    </Wrap>
+  );
+
+  const loginLink = await screen.findByRole('link', {name: 'Login with DigiD'});
+  expect(loginLink).toHaveAttribute(
+    'href',
+    'https://openforms.nl/auth/form-name/digid/start?next=http%3A%2F%2Flocalhost%2F%3F_start%3D1'
+  );
+});